As an image recording apparatus for recording an image on a recording medium by ejecting ink thereto on the basis of an input signal, an image recording apparatus for supplying ink to an actuator of a recording head and pressurizing and ejecting ink by the use of a warping of the actuator such as a piezoelectric element and an electrostriction element or local boiling of ink by a heating element has been known.
For example, in an image recording apparatus called a serial printer, a recording head is mounted on a carriage reciprocating in the direction perpendicular to a transport direction of a recording medium. The carriage reciprocates to perform an image recording operation every time when the recording medium is transported with a predetermined linefeed length. In order to control the recording head, a flexible conductive wire called a flat cable is connected to the carriage. The flat cable has a length enough to follow the reciprocation of the carriage so as not to hinder the reciprocation of the carriage and is curved in a substantial U shape between the carriage and a main board (for example, see JP-A-6-320835).
FIG. 13 is a diagram illustrating a carriage 90 and a flat cable 91 of a conventional image recording apparatus. The carriage 90 reciprocates in the direction perpendicular to the transport direction of a recording sheet and an image is recorded on the recording medium by ejecting ink from a recording head not shown. The flat cable 91 for transmitting and receiving an electrical signal to and from the main board is connected to the carriage 90. An end 92 of the flat cable 91 is fixed to a frame not shown and is wired to the main board from the end 92. Although not shown in the figure, the carriage 90 is supported by a guide member such as a guide shaft or a guide rail and supplied with a driving force from a belt driving mechanism, etc.
As shown in the figure, the flat cable 91 is drawn out substantially in a horizontal direction from the carriage 90 and is curved substantially in a U shape. When the carriage 90 reciprocates, the flat cable 91 moves accordingly and the central position of the U-shaped curved portion also moves. As indicated by a two-dot chained line in the figure, the posture of the flat cable 91 is changed so that the diameter of the U-shaped curved portion increases when the carriage 90 moves to right and the diameter of the U-shaped curved portion decreases when the carriage 90 moves to left.
Since a decrease in size is required for the image recording apparatus, it is preferable that the space for changing the posture of the flat cable 91 is made as narrow as possible. However, when the flat cable 91 is too close to another member, the flat cable 91 may be damaged due to contact with another member at the time of changing the posture of the flat cable 91. The damage of the flat cable may cause a short-circuit in a conductive wire therein. In addition, a moving speed of the carriage may become unstable due to a load generated from the contact of the flat cable with another member, thereby disturbing the image quality of the recorded image. In order to solve such a problem, means for controlling a movable range of the flat cable 91 at the time of changing the posture thereof has been proposed (for example, see JP-A-9-109508, JP-A-2002-11918 and JP-A-2003-11340).